Powerbook 100 (continued)

[novastar]

Hey guys, I have some updates regarding the PB100 restoration I began documenting in http://www.vintage-computer.com/vcforum/showthread.php?46603-Powerbook-100.

This machine is now almost completely restored. I've recapped everything including the screen.

I was even able to repair the 20MB Conner HD; the head was sticking to a rubber surface which I guess acted as the park lock as opposed to the moving mechanisms in other drives. I simply covered the rubber surface with some tape and now it works like a champ; quite operation, no errors, no more stiction. I've actually fixed several Conners with this 'technique'.

However, the machine will not keep the date/time or the contents of the RAM disk if the power is disconnected. I've added new battery coin cells and tried the connect/disconnect battery switch in both positions. There is no main battery in the bay however and I've not touched the switch in there.

I'm beginning to think that I damaged the battery circuit when I swapped out all of the caps. Is there anyway to check this? For what it is, the internals of this little machine seem quite complicated.

I also want to run System 7.1 on the PB100 but every attempt to boot it from a 7.1 floppy has failed so far. I get either a sad mac or a 'this system cannot be used with this mac' message. Is there a specific version or enabler that I need to use? I've had no problem with System 6 and System 7.0.1.

 

[Capt. 2110]

Cool!

You might have still put dying batteries in. Did you buy them new, or take them from a pile of batteries?

Just make sure all of the caps are in the right direction with no shorted pins and make sure none of the caps lifted off of the pads. Also, did you use any substitute caps? Like instead of 6.3v 1300UF, you used 10v 1300UF?

Something is wrong then. Very wrong. http://apple-history.com/100

You might need to make a new floppy for 7.1. If so, you can get the .IMGs here. https://winworldpc.com/product/mac-os-7/71

Good luck, and I hope you get everything working!

 

[novastar]

I've confirmed the batteries are good, all three produce 3.65v. I couldn't see any lifted pads and I checked the polarities. I was careful to use caps of the same values; in some cases I had to use a higher voltage rating but never lower.

I'm at a loss. It's especially frustrating because control panel settings are also preserved in RAM. Does anyone know how the battery power circuitry works in these things?

 

[novastar]

Well I'm an idiot. It turns out the batteries were too low. I bought them new but must have gotten a bad batch. I just tried some other ones and now the RAM disk is preserved. Combined, the latest batteries provide 9.5v. It seems it takes quite a bit of juice to preserve the RAM; clearly this was intended as a temporary thing while the main battery is low.